The present invention relates generally to data communications. More particularly, the present invention relates to direct link setup mechanisms for wireless local-area networks (WLAN).
Wireless local-area networks (WLAN) have become increasingly popular for communicating data between electronic devices. WLANs are frequently operated in infrastructure mode, where a wireless access point relays data between the electronic devices, which are referred to as wireless clients. Each communication between two wireless clients in infrastructure mode requires two sequential transmissions: from the sending wireless client to the wireless access point, and from the wireless access point to the receiving wireless client. In many cases, a direct link between the two wireless clients would be preferable.
Direct link setup (DLS), which is described in IEEE standard 802.11e, provides this capability. FIG. 1 shows a conventional IEEE 802.11 WLAN 100 comprising a wireless access point 102 passing traffic between two wireless clients 104A,B in infrastructure mode over connections 106A,B respectively. DLS allows wireless clients 104A,B to establish a direct connection 108. However, DLS as specified by IEEE 802.11e has several limitations.
IEEE 802.11e requires that wireless clients use the same channel for DLS as for the Basic Service Set (BSS) to which they belong. This is an unnecessary restriction if other channels are available for use. Furthermore, IEEE 802.11e DLS explicitly disables legacy power-save and Automatic Power-Save Delivery (APSD), resulting in increased power consumption for wireless clients operating in DLS mode. IEEE 802.11e DLS also does not define the precise conditions for initiating/tearing-down a DLS session or the operating parameters to be used during a DLS session. In addition, IEEE 802.11e DLS does not specify a specific protection mechanism to be used during DLS data transfer in order to mitigate interference from other traffic sources.